The present invention relates to a grease composition for a constant velocity joint or a fixed type joint and slide type joint.
In general, a combination of a fixed type joint, a shaft and a thrust type joint is employed when a constant velocity joint is applied in FF type or front wheel driven type cars.
Examples of fixed-type joints include Birfield joints, Rzeppa joints, undercutting free joints and tripod joints. Examples of slide-type joints include double off-set joints, tripod joints, and closs groove joints.
Constant velocity joints are generally lubricated with an extreme pressure grease made up of a base grease consisting of a purified mineral oil, a lithium soap and an urea thickner which is combined with molybdenum disulfide, a sulfur-phosphorus compound, a lead compound, etc.
In the grease composition for the constant velocity joint, there are required characteristics such as anti-flaking, anti-seizure, abrasion resistance or low friction properties. However, conventional grease compositions are generally lacking in these areas. In particular, in the view of a prolonged life time of the constant velocity joint, it has been desired to improve the anti-flaking performance.